Solubilization of Violacein in Water/Sodium Dodecyl Sulfate System: Molecular Dynamics Study

Abstract

Violacein, a well-known microbial pigment isolated from Chromobacterium violaceum that shows a wide range of application in medicine, cosmetics and textile industries. Its production has attracted many attentions for research and application due to its diverse biological activities including antibacterial and antioxidant properties. However, violacein was reported to be insoluble in water in which it is commonly dissolve in harmful solvent such as dimethyl sulfoxide and methanol. The solubility of violacein in water could be improve with the aid of surfactant by which at above the critical micelle concentration (CMC), the surfactant will form a micelle and allow the violacein to assimilate inside it, making the violacein to be soluble in water. This study focuses on the solubility of violacein in water/surfactant system through molecular dynamics approach where the surfactant used was sodium dodecyl sulfate (SDS). In details, the coarse grain method was applied to stimulate the solubilization behaviour of the violacein, where all the molecules involve are represented as beads. Each bead was assigned with charges and force field based on their natural behavior and structure. Consequently, at above CMC point, the SDS formed a spherical micelle at 91.60 ns and been able to solubilize the violacein in water. From the radial distribution function (RDF) analysis, higher peak was obtained for interaction of violacein with the hydrophobic part of SDS at radius equals to 5.125 Å compared to the hydrophillic part. In conclusion, the violacein beads were more attracted towards the hydrophobic part of surfactant compared to the hydrophillic part. In short, the coarse grain method can be applied to study the solubility of violacein in water/surfactant system. The finding may help to study the interaction of violacein with other materials which would widen its application in industries.